Sample code for Java Memento pattern implementation
Sample code for Java Memento pattern implementation
/** * 数据对象 * @author stone * */ public class DataState { private String action; public void setAction(String action) { this.action = action; } public String getAction() { return action; } }
/** * 一个保存另外一个对象内部状态拷贝 的对象.这样以后就可以将该对象恢复到原先保存的状态. * * @author stone * */ import java.io.File; import java.io.Serializable; public class Memento implements Serializable { /*private int number; private File file = null; public Memento(Originator o) { this.number = o.getNumber(); this.file = o.getFile(); } public int getNumber() { return this.number; } public void setNumber(int number) { this.number = number; } public File getFile() { return this.file; } public void setFile(File file) { this.file = file; } */ private DataState state; public Memento(Originator o) { this.state = o.getState(); } public DataState getState() { return state; } public void setState(DataState state) { this.state = state; } }
public class Originator { /* private int number; private File file = null; public Originator() { } // 创建一个Memento,将自身作为参数传入 public Memento getMemento() { return new Memento(this); } // 从Memento中取出保存的数据,恢复为原始状态 public void setMemento(Memento m) { number = m.getNumber(); file = m.getFile(); } public int getNumber() { return number; } public void setNumber(int number) { this.number = number; } public File getFile() { return file; } public void setFile(File file) { this.file = file; }*/ private DataState state; public Originator() { } public Originator(DataState state) { this.state = state; } // 创建一个Memento,将自身作为参数传入 public Memento getMemento() { return new Memento(this); } // 从Memento中取出保存的数据,恢复为原始状态 public void setMemento(Memento m) { /* * getMemento() 创建的对象,保存在某个容器里, * 当需要恢复时,将其传入当前方法, 再使用getState(),得出 */ this.state = m.getState(); } public DataState getState() { return state; } public void setState(DataState state) { this.state = state; } }
/* * 备忘录(Memento)模式 行为型模式 * 流程: Memento用于保存 数据状态, * Originator用于 加载数据, 建立Memento对象,及通过Memento恢复原始数据 */ public class Test { public static void main(String[] args) { // Originator originator = new Originator(); // originator.setNumber(8); // // Memento memento = originator.getMemento(); // System.out.println(memento.getNumber()); DataState state = new DataState(); state.setAction("copy a character"); Originator originator = new Originator(); System.out.println("创建原始数据"); originator.setState(state); System.out.println("创建备忘录对象, 保存原始数据状态"); Memento memento = originator.getMemento(); System.out.println("创建了一个新数据"); originator.setState(new DataState()); System.out.println("创建新数据后:" + originator.getState().getAction()); /* * memento 需要保存在某地,需要时取出,以恢复它内部所保存的数据 */ System.out.println("创建新数据后,恢复原数据"); originator.setMemento(memento); System.out.println(originator.getState().getAction()); } }
创建原始数据 创建备忘录对象, 保存原始数据状态 创建了一个新数据 创建新数据后:null 创建新数据后,恢复原数据 copy a character
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